Arrows coming down verticcally have lost almost all their kinetic energy and would be unlikely to do any harm at all. French horses did have armour or padding. There is absolutely no evidence for the English using bows to "arc" arrows into the enemy. Almost all iconography, as well as practical tests with modern replicas like this video, indicates that you need to shoot flat and you need to be relatively close, to do damage.

My understanding is that the original Welsh use of the Longbow was more in line with their guerrilla/ambush tactics - namely the shot would be taken at relatively close range, from cover, on a flat trajectory, and would have substantial penetrative power as a result.